Abstract: The relative position relationship between the robot and the leading line is divided into seven typical states,according to which the control system adopts an adjustment strategy respectively.An implementation principle using this me-chanism design is demonstrated by which the chassis centerline can approach the leading line gradually through continuously adjusting the chassis posture.Based on MSP430,the speed difference between the left and right wheels is produced by the Pulse-Width Modulation to adjust the relative position of the robot and the leading line,and quick,stable and accurate line-tracking is realized.